Saturday, July 24, 2010

As Monty has been working hard to make Cinelerra more input friendly with his FFmpeg loader fixes, I've been trying to help out as a QA resource. One of my main concerns has been getting my Canon 5D video into Cinelerra. As documented in the IRC log, my custom Canon conversion (ffmpeg stream -> mpeg2enc (output: .m2v/.m2a) -> mplex (output MPEG-PS) -> ffmpeg (output MPEG-TS) was full of invalid timestamps.

In addition, with some recent security updates to my Fedora system just today, it looks like my previous Canon conversion script had broken. I get the dread error:

**ERROR: [mpeg2enc] display_horizontal_size must be in range 0...16383

So I was doubly screwed. Back to the drawing board..er, mailing list. Following up on mjpegtools' Bernhard Prachinger's advice here, I first try to play a test file using a pipe from ffmpeg, like so:ffmpeg -i mvi_2655.mov -threads 7 -s 1920x1088 -f yuv4mpegpipe - | yuvplay

This gives me a good program stream file that is suitable for editing in Cinelerra using Monty's changes. Update 2010/09/13: Florian Cramer advised me that the video render string does not give the highest quality output. I'm still working on improvements to the string that will render at a higher quality.

Friday, July 16, 2010

Unbelievably, just in the past week, the Cinelerra CV community (http://cvs.cinelerra.org/) has had a heavyweight developer parachute in and start fixing stuff all over the place. The guy is Chris "Monty" Montgomery who developed the Ogg multimedia container and Vorbis audio formats (http://en.wikipedia.org/wiki/Chris_Montgomery). He is a developer currently working for Red Hat.

Monty, You're The Man!His primary effort has been to yank out the kludgy and incompatible file loader in Cinelerra and replace it using good old FFmpeg. FFmpeg has problems of its own, but a helluva lot less problems than the Cinelerra loader. This is a task that the original developer of Cinelerra, Heroine Warrior (http://www.heroinewarrior.com/), has wisely done with the 4.1 version of Cinelerra. Much props to Father HV, for without him, this blog and Open Source video editing would be very different, if exist at all.

Monty is patching the version of FFmpeg that comes with the Cinelerra CV source code (http://cinelerra.org/getting_cinelerra.php). In Cinelerra CV's source code tree, FFmpeg is found under quicktime/ffmpeg. This means that once you compile Cinelerra from source code and add Monty's code fixes, files like the Canon 5D/7D H264 AVC files (the 1080P files spat out of the Canons') will load natively in Cinelerra.

AVC, oh AVC, Why Are You So Stubborn?Problem here is that you can't really edit with AVC files because the decoding of them is so bloody CPU intensive. AVC playback in Cinelerra on my dual, quad core Dell SC1430 with 10GB RAM is 3-4fps. This is unacceptable for previewing edits. There is a workaround to this such that if you really wanted to edit AVC, you'd need to have background rendering enabled, make your edits and then wait for the background render to finish. But that bg render takes a long time too. You could speed this up to by creating a ramdisk (http://www.techanswerguy.com/2009/02/creating-ramdisk-in-linux.html) and setting the background render to use that ramdisk. But that's a whole other task.

Transcoding Canon 5D/7D Files, as usualThus, we're still left with the task of transcoding Canon 5D/7D files into a more compatible format. There are two solutions:1) get my varied MPEG-TS conversion magic to work for you (http://crazedmuleproductions.blogspot.com/2009/02/dark-of-winter-has-me-in-its-grasp.html)2) convert the 5D/7D files using FFmpeg into another format that works since FFmpeg is now Cinelerra's loader (with Monty's additions)

The audio format is mpeg, layer II and the video format is mpeg2video. This loads in Cinelerra and is fast to edit with. Once edited, render out from Cinelerra as usual.

How to Compile Cinelerra for Ubuntu and Fedora usersSo Monty's additions require compiling from source. I'll provide some quick links here. For Ubuntu folks, Raffaella Traniello has put a nice post together on how to compile Cinelerra in Ubuntu:http://www.g-raffa.eu/Cinelerra/HOWTO/compilation.html

I then was able to switch branches[mule@ogre my_cinelerra]$ git checkout -b xiphmont xiphmont/masterBranch xiphmont set up to track remote branch master from xiphmont.Switched to a new branch 'xiphmont'

Show the current status of the git code repositories[sfrase@ogre my_cinelerra]$ git status | head -6# On branch xiphmont# Untracked files:# (use "git add ..." to include in what will be committed)## cinelerra-cvs-current.spec# cinelerra/.deps/>

Why Mule?

"Mules are not really stubborn. They can seem lazy because they will not put themselves in danger. A horse can be worked until it drops, but not so with a mule. The "stubborn" streak is just the mule's way of telling humans that things are not right. Mules are very intelligent and it is not a good idea to abuse a mule. They will do their best for their owner, with the utmost patience."About Mules